The invention is directed to a current measuring module for a starter device of internal combustion engines with a measuring device which measures a starter current of a starter motor.
It is known that internal combustion engines must be started by means of a starting mechanism because they cannot start by themselves. Starter motors are usually used for this purpose. These starter motors are connected with a voltage source via a starter relay constructed as an engagement relay, as they are called, and a pinion of the starter motor is simultaneously engaged with a toothed rim of a flywheel of the internal combustion engine for cranking. In order to switch on the starter relay, it is known to control this starter relay by means of an external switch, for example, an ignition switch or starter switch of the motor vehicle. After the internal combustion engine has begun to run independently, the starter motor must be disengaged to prevent noise and wear. It is known to switch off the starter manually by releasing the ignition switch or starter switch. Solutions for turning off the starter of the internal combustion engine automatically for increased convenience in motor vehicles are known. In order to detect independent running of the internal combustion engine, an evaluation of a starter current can be carried out. The fact that the starter current changes its shape depending on the independent running of the internal combustion engine is made use of for this purpose. When the internal combustion engine reaches its independent running rotational speed, i.e., develops its own torque, the starter motor is overtaken with respect to its rotational speed, wherein the starter motor is separated from the internal combustion engine by a freewheeling clutch. From this point, the starter motor need only apply its own acceleration torque, so that the starter current drops to the idle current or no-load current. Therefore, when the starter motor reaches the no-load current, this signals the independent running of the internal combustion engine.
It is known from general electronic engineering that a conductor carrying current is surrounded by a magnetic field proportional to the current.